Flutter CoreIntermediate30 XP3 min read
Explain JIT vs AOT compilation in Dart/Flutter
TL;DR: JIT (Just-In-Time) compiles Dart at runtime in Debug mode, enabling hot reload but slower startup; AOT (Ahead-Of-Time) compiles to native machine code at build time for Release, giving faster startup and smaller memory footprint.
Full Answer
| Aspect | JIT | AOT |
|---|---|---|
| When compiled | At runtime | At build time |
| Hot reload | Supported (patches VM) | Not possible |
| Startup time | Slower | Fast |
| Peak performance | Can optimize hot paths | Fixed compiled output |
| Used in | Debug mode | Release mode |
🎯
Tree shaking is a benefit of AOT: the Dart compiler removes unused code at compile time. A typical Flutter release APK is smaller than you'd expect because dead code is eliminated.
Interview Tip
💡
Dart's AOT compilation is what allows Flutter to achieve truly native performance — the resulting binary is native ARM64 code, not bytecode being interpreted.
#jit#aot#compilation#performance#dart-vm